WARNING! POLAR HEART RATE MONITORS DEFECTIVE!

I think most people trying to lose weight the calories burned is the most important stat for them.

Just looking at the raw data though you must see something is amiss. Without changing any other variables when you increase the weight the calories burned goes down. It simply does not make sense.

Thank you all for your input and observations.

After all the input I've heard so far the conclusion is still the same

The higher the weight you enter on the Polar FT7 the more likely that it is not accurate.

For example, at 300 pounds or above it appears to be between 30-50%. Surely it must vary 0-20% from reality depending on a lot of factors from individual to individual but the numbers I'm getting a just way off. This is also true for a lot of other people posting here, especially at higher weights. Something is surely amiss.

In short, while the mechanical work is the same and the load did not change the muscular efficiency does change (fiber recruitment, neurological changes, mitochondrial whatnot, and even muscle fiber type over long term) and muscular work has a large thermal component that is not the same in the two cases. From my human physiology courses (in the last century) mechanical work only corresponds to about a quarter of metabolic energy use; it's the other components of energy use that are also changing. Therefore the metabolic calories consumed are not the same in this example for the fit and not fit. While VO2max does increase with training and probably remains the best measure there are significant efficiency gains that do not translate to VO2max gains.
Examples of this are all the elite cycling studies where VO2max goes slightly down with increased work/power capacity.
And of course, that woud be another example of issues with HRM used to calculate "burn".

And there is the whole confusion between relative and absolute V02max. As you likely know, two individuals with the same absolute V02max will have different fitness levels depending on their weight.

In short, while the mechanical work is the same and the load did not change the muscular efficiency does change (fiber recruitment, neurological changes, mitochondrial whatnot, and even muscle fiber type over long term) and muscular work has a large thermal component that is not the same in the two cases. From my human physiology courses (in the last century) mechanical work only corresponds to about a quarter of metabolic energy use; it's the other components of energy use that are also changing. Therefore the metabolic calories consumed are not the same in this example for the fit and not fit. While VO2max does increase with training and probably remains the best measure there are significant efficiency gains that do not translate to VO2max gains.
Examples of this are all the elite cycling studies where VO2max goes slightly down with increased work/power capacity.
And of course, that woud be another example of issues with HRM used to calculate "burn".

And there is the whole confusion between relative and absolute V02max. As you likely know, two individuals with the same absolute V02max will have different fitness levels depending on their weight.

Ya, I love that running pace estimates that take your VO2max and calculate a pace you should be able to do. Without weight being asked for. Ya, I'll run my knees and feet into the ground maintaining that 7 min pace for oh, 3-4 miles right now.

I'm thinking running might see better efficiency gains.
I used the walking example because of the tight bell curve on energy spent walking different speeds. I don't think you'd see significant efficiency gains if you'd done any walking. Just not used to doing it for a long time.
But really, some of what you describe as changing and improving efficiency, is exactly why the VO2max improves, and HR lowers, to provide the same oxygen to a system that is much more efficient at using it now. So the energy use is a whole lot tighter I'd believe unless you are comparing different people, or really improving your running, biking, swimming efficiency.

Like the study of cyclist and optimum cadence. Rider naturally selected wasn't the most efficient, but it gave better results over all. Pro-cyclist, so they knew what felt like their own best efficiency.

Oh, the study showing how tight the calorie burns are for walking.

http://www.ncbi.nlm.nih.gov/pubmed/15570150

While it was mainly talking about the calculation predictions, the measured expenditure is within 5 calories when weight adjusted. We seem to walk at certain speeds with pretty equal efficiency since we've been doing it for so long. Once we can pull ourselves off the bike anyway.

Well, there was a RS300X for sale at a nearby store (going out of business) so I picked it up. Here is a last data point for your discussion, Peter.

Two watches, one HRM strap.

My data: Age 46 MaxHR 189 VO2Max 47 Sitting HR 60 Actual weight 85 Kg
--
Exercise was running for 41 min - both watches gave MaxHR 179 (95%) Avr HR 164 (87%)

-- FT7 -- Weight set 145 Kg Calories 503
-- RS300X -- Weight set 85 Kg Calories 642

So, this is just a data point - I think Haybales describes above what is going on and I don't have much issues with the readings, even at the lower calorie burn - someone weighing 145 calories could not have run 10kph for 41 min at that average HR without being incredibly, incredibly fit.

I wasn't going to execute today's data gathering like that but I forgot to set the FT7 back to 85Kg.

All future comparisons will be more about what the two watches give at 85Kg with the same MaxHR. But that wil be a different thread.

Height 179.5 but I round to 180 cm.
Yep it has the VO2max, sitting HR and max HR. I don't know if it uses sitting HR in Cal calcs.

What I'll do is set up two straps (Garmin vs Polar) and run the following HRM / gps against each other.
Garmin 800, 405, Polar FT7, RS300X, mapmyfitness - all at the same time.
My daughter has a FT4, so might toss that one into a test if she brings in back from college.

Maybe first test will be Thursday, that my next run.

Here is another interesting article. I think the main point of it though is that HRM are better than Fitbit and other devises in measuring calorie consumption. It makes me wonder if all the fitbit devises are really quite useless for the most part. I've never owned one though.

But still, this does not answer the Polar FT7 calorie burn going down as weight increases.

http://www.wired.com/playbook/2012/08/fitness-trackers/

Height 179.5 but I round to 180 cm.
Yep it has the VO2max, sitting HR and max HR. I don't know if it uses sitting HR in Cal calcs.

What I'll do is set up two straps (Garmin vs Polar) and run the following HRM / gps against each other.
Garmin 800, 405, Polar FT7, RS300X, mapmyfitness - all at the same time.
My daughter has a FT4, so might toss that one into a test if she brings in back from college.

Maybe first test will be Thursday, that my next run.

If that's the model with a fitness test, it'll measure your sitting HR, and use it in an estimate of your VO2max. Their website has a FAQ on the study they tweaked, I use it in the spreadsheet too for VO2max estimate.

If it measured 60, it should estimate about 45.5.

Or you can manually enter it as you did.

To get that to 47 that you know already, you'd have to enter height of 190 cm.

But your tests first will be interesting.

I have the polar ft4 and it's the same thing. It doesn't even make sense to me why a heavier person would burn LESS than a lighter person having the same HR.